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Union Neptune

Name
Union Neptune
Accident date
22/07/2011
Location
France
Accident area
Bay of Biscay
Spill area
Offshore
Cause of spill
Loading/unloading
Product transported
iron oxyde
Quantity transported
2,238 tonnes
Nature of pollutant
iron oxyde
Quantity spilled
2,238 tonnes
Ship / structure type
Cargo vessel
Length
83.00 m
Width
11.00 m
Draught
3.94 m
Flag
Cook Islands

The incident

On 20th July 2011 in Bassens (Gironde, France), the cargo vessel Union Neptune loaded 2,238 tonnes of iron oxide, which had been refused by the receiver a few months earlier due to the quantity of water covering the cargo when it was delivered. The loading operation was partly carried out in the rain. On the 21st, the vessel, registered in the Cook Islands, set sail for Rotterdam. At around 11:30 pm, the Union Neptune showed a constant 5° to 7° starboard list, despite the starboard ballast tanks being empty. Several attempts were made to correct the list but were unsuccessful. The commanding officer therefore decided to return to Bassens.
By around 2 am on the 22nd, the ship was 45 km west of the Pointe de la Coubre (Charentes) and was showing a 30° to 35° list to port. The commanding officer requested immediate assistance and the six crew members left the vessel on a lifeboat.

The response

The crew was airlifted to safety during the night by a French Navy helicopter deployed from MRCC Etel.
After having given the shipowner formal notice to take the necessary measures to ensure safe navigation and to eliminate the pollution risk and the hazard caused by the wreck, the French authorities prepared for operations to ensure the safety of the vessel and its cargo.
On the afternoon of 23rd July, the Union Neptune was taken in tow by the Abeille Languedoc, but its list increased further. Late afternoon, it partially sank off the island of Oléron. It lay in waters 35 m deep, but its bow continued to float and could be seen at the surface. Vessels and aircraft carried out daily surveys of the area.
On the 27th, two buoys were moored near the wreck to reinforce navigational safety measures. The majority of the cargo was released when the hatch covers broke as the ship sank. Samples were taken by the French Navy LASEM laboratory in Toulon to assess whether or not the cargo should be recovered.
Due to heavy swell combined with strong currents and spring tides, the wreck began to drift. The French authorities decided to sink the vessel. On 12th August, following inspection of the hull, French navy clearance divers gradually opened breaches in the wreck using explosives, while striving to preserve its integrity as much as possible and prevent pollution. By late afternoon, the wreck lay stable in waters 45 m deep with over 30 m of water above it.

Post-incident analysis

According to the report published by the French marine accident investigation office in early 2012, this incident can be explained by a combination of several factors.
Approximately 1,400 litres of rainwater was "mixed" with the iron oxide when it was loaded in Bassens, which was partially responsible for causing the Union Neptune to lose its stability. The metocean conditions in the area were an aggravating factor.
In addition, it appears that the significant list may also have been due to shifting of the cargo together with a free surface effect caused by the water absorbed by the iron oxide having risen to the surface. The "change of state" of part of the cargo, due to the high humidity level and significant quantity of water in the holds, appears to have been the determining factor causing the vessel to sink.

Sources

-    Communiqués de presse N°1 à 7, Préfecture maritime de l’Atlantique, Juillet et Aoû 2011
-    Liquéfaction partielle d’une cargaison d’oxyde de fer : un fluvio-maritime coulé, Michel Neumeister, Journal de la marine marchande, 20 Janvier 2012
-    Rapport d’enquête technique Union Neptune, Bureau d’enquêtes sur les événements de mer, 2012

Last update: 10/02/2017